MC1R基因在中国草金鱼中的遗传变异及其进化分析

A Study of Genetic Variation and Evolutional of MC1R Gene in Chinese Goldfish

鱼类的体色具有重要的观赏和经济价值,是重要的品种特征,属于高遗传力的质量性状,通常受单个基因或几个基因控制。MC1R基因在黑色素合成过程中起着重要的调控作用,因此可能参与鱼体色的形成。研究利用中国草金鱼为材料,对MC1R基因进行全长序列扩增、SNPs搜寻及其突变位点的功能与进化分析。结果在MC1R基因整个序列上只鉴定到1个突变位点,即Exon1 g.82 G>A,属于错义突变,该突变导致MC1R基因的第28个氨基酸发生改变(丙氨酸>苏氨酸)。进一步蛋白质结构预测和功能分析发现该突变导致MC1R蛋白形成了一个新的低复杂区。通过MC1R基因的分子进化树分析发现金鱼与鲫鱼、鲤鱼、斑马鱼等最先遗传分化出来,它们的遗传距离最近。MC1R基因的Exon 1 g.82 G>A突变位点是否在金鱼体色的形成中起着重要调控作用还有待进一步研究。

Coat color is the main characteristic of fish.It exhibits the important viewing and economical values of fish.Studies have showed that coat color is a high heritability of quality traits and is always affected by one single gene or more genes.MC1R gene plays an important role in melanin biosynthesis,so it is a candidate gene influencing fish coat color.In this study,the genetic variation and evolution of MC1R gene in Chinese goldfish and wild crucian carp were analyzed.As the result,only one mutation （Exon 1 g.82 G〉A） was identi-fied in the whole-length gene sequence.This SNP is a missense mutation leading to the transversion of Ala to Thr at the site of 28th amino acid of MC1R gene.The results from protein structure prediction and functional a-nalysis demonstrated that a new low complex area of MC1R protein was formed by the missense mutation.Phy-logenetic tree study showed that the genetic distance between Goldfish and Crucian carp,Carp and Zebrafish is shortest,owing to the earliest genetic differentiation.But whether Exon 1 g.82 G〉A of MC1R gene plays an im-portant role in fish coat color or not needs further investigation.